Ruins of Aose Castle are located close to the port of Åhus. This fortress, probably built in the 12th century and again in 1286, was protected by a high wall and a moat spanned by a drawbridge. It was destroyed in 1569 by Duke Karl, later to become King Karl IX of Sweden, and the ruins were gradually covered by drifting sand before being excavated in the late 1800s. It has always been widely assumed that the castle was built on the orders of Archbishop Eskil, but recent excavations have revealed new evidence that suggests that Canute the Great, King of Denmark and England, was the first lord of Aose Castle.
References:The Citadelle of Quebec is an active military installation and official residence of both the Canadian monarch and the Governor General of Canada. It is located atop Cap Diamant, adjoining the Plains of Abraham in Quebec City. The citadel is the oldest military building in Canada, and forms part of the fortifications of Quebec City, which is one of only two cities in North America still surrounded by fortifications, the other being Campeche, Mexico.
The first fortifications in Quebec were built by the Governor General of New France Louis de Buade, and completed just in time for the Battle of Quebec in 1690.
After the British conquest in the second half of the 18th century, the problem of Quebec City's defences grew more acute.